The present disclosure relates generally to communication systems, and more particularly, to full duplex communication in the presence of mixed full and half duplex users.
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of an emerging telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP), It is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
Conventionally, the signals in the uplink (UL, or reverse link) and the signals in the downlink (DL or forward link) are transmitted either in different frequency hands (e.g., by frequency domain duplexing (FDD)) or in the same frequency band but in different time slots (e.g., by time domain duplexing (TDD)). This method of separating UL and DL transmissions is referred to as half duplex (HD) communication. The separation of the signals in either frequency or time domain eliminates the possibility of a strong transmit signal of a user to drown a weak signal received by that same user. However, there may be users that have full duplex (FD) capability, hereinafter referred to as FD capable (FDC) users, such as users that are equipped with an echo canceller which allows them to receive and decode signals while also transmitting. In the existing radio access technologies (e.g., LTE), such FDC users are conventionally serviced as legacy users with no FD capability.